They're referring to the leaky network toggles in LineageOS for different kinds of networks. GrapheneOS won't include that because it doesn't work correctly and gives people the false impression that it's going to stop apps communicating over those networks when it only stops most (not all) direct connections.

LineageOS has the same Seedvault backup system with the same limitations. There are few limitations left since Android 12's API level stopped apps opting out of all backups by redefining it as an opt-out of cloud backups and similarly redefined the file exclusions as only being for cloud backups. The new system supports very explicitly omitting files from device-to-device backups but it has to be explicitly specified that way and few apps do it. The problems with apps opting out of backups due to not wanting cloud backups for space, bandwidth or privacy reasons has been solved for several years now. It doesn't mean all app data is portable between devices, such as Signal encrypting their database with a hardware keystore key making it fundamentally impossible to do backups at a file level for it rather than using their own backup system.

See https://news.ycombinator.com/item?id=45562664 for a response to the rest of it.